Bi-directional text

Scripts like Hebrew and Arabic, that are normally thought of as right-to-left, are in fact bi-directional, since they often use the so-called
'Arabic' numerals, i.e., the western-style 0, 1, 2,..., which are written from left to right. It is also quite common for an English word to find
its way into a right-to-left script, much more than vice versa.

No `visual order'

In e-mail, right-to-left and bi-directional text has sometimes been simulated by simply reversing the order of the characters.
IANA
even has an official `charset' for visually ordered Hebrew in e-mail: iso-8859-8. In HTML visual ordering is impossible (unless the whole
document is placed in <PRE>...)

When an HTML browser finds a document labeled as iso-8859-8, it should therefore
not
assume the text is visually ordered.